This influx of high-paying jobs (averaging $60 per hour) is expected to draw a significant number of professionals to the area, boosting demand for housing and various services.

If I create a debt fund that offers 9% interest on first lien notes with a 5-7 year payout, would that be attractive to high net worth investors?

I would highly recommend a mentor or even paying a coach to get started.

People with high risk tolerance will have a far different answer than someone who is risk averse. 

Much better as a short term acquisition strategy for flips IMO but always a high-risk strategy that should not be practiced by anyone who doesn't have the liquid capital to pay off the loan if needed.

You avoid the tax hit, and still get the use of 75% of the equity if you do a cash out refi - (but high interest rates sort of play against that to some degree presently… but you could alway refi again down the line if rates dropped.  

Rent growth is a function of supply, demand, and interest rates:- I'd ground any forecast by stating I expect national rents to rise on a pace more or less in line with inflation over any long time period. 2-3% per year.

Cleveland is great for that high cash-flow.

I highly encourage everyone to view the property before putting money down, but that's not ideal for many of them, so I do allow them to rent "sight unseen," but I am very open with them to ensure they don't show up and back out.1.

I'd highly recommend attending some local reia meetings.